Sites of Metastases of Anaplastic Thyroid Carcinoma: Autopsy Findings in 45 Cases from a Single Institution

Background: Despite surgical treatment, chemotherapy, and/or radiotherapy, the vast majority of patients with anaplastic thyroid carcinoma (ATC) have a dismal prognosis. Better knowledge of the frequency of metastases to different sites might help us to perform the appropriate diagnostic tests before treatment and during the course of the disease. The aim of this study was to determine the frequency of metastases from ATC in different sites as found at autopsy. Methods: Altogether, 205 patients were treated for ATC at our institute during the years 1972-2008. Autopsy was performed in 45 cases (30 females, 15 males; median age 66 years). The relative frequencies of metastases in different sites were analyzed using descriptive statistics. Results: Altogether, 41 cases (91%) had metastases at autopsy. The most common sites of metastases were the lungs (78%), intrathoracic lymph nodes (58%), neck lymph nodes (51%), pleura (29%), adrenal glands (24%), liver (20%), brain (18%), heart (18%), and retroperitoneal lymph nodes (18%). Less common sites of distant metastases were the pericardium (13%), bones (13%), kidneys (13%), mesentery or peritoneum (13%), skin (9%), pancreas (4%), stomach (4%), diaphragm (4%), pituitary gland (2%), ovary (2%), jejunum (2%), axillary lymph nodes (2%), and gingival mucosa (2%). Both distant and regional metastases were present in 23 cases, while only distant metastases were present in 18 cases. An extensive local infiltration of the primary tumor was found in 76% of the cases. The total number of the involved organs and lymph node basins were 123 and 58, respectively. The mean number of metastatic sites was 4.02 +/- 2.75. Lung metastases were present in 34 of 38 (89%) of our patients who had distant metastases found at autopsy. Of these 34 patients, 27 were known to have lung metastases when they were alive. Conclusion: Two or more metastatic sites were found at autopsy in 84% of cases. The most common metastatic sites are lungs, followed by the intrathoracic and neck lymph nodes.